Lithium ion batteries which can be utilized as the motive power for vehicles have been enthusiastically developed in recent years. Particularly, batteries using, in a negative electrode, an active material which has a high potential typified by lithium-titanium composite oxide are superior to batteries using a carbon negative electrode in life characteristics, safety and rapid chargeability. Batteries using such a lithium-titanium composite oxide are also expected to have longer life.
JP-A 10-69922 (KOKAI) discloses a nonaqueous electrolyte lithium secondary battery which is improved in over-discharge resistance and over-charge resistance by using, in the negative electrode, a lithium-titanium oxide having high stability in a wide potential range and also, by making the capacity of the negative electrode smaller than that of the positive electrode. The above nonaqueous electrolyte lithium secondary battery is further developed into a battery disclosed in JP-A 2000-12090 (KOKAI) in which the ratio of the actual capacity of the negative electrode to that of the positive electrode is designed to be 0.8 or less. However, a battery having the structure disclosed in the above document has the problem concerning a shorter cycle life.